Studying Galaxies, Galaxy Clusters, and Cosmology with Weak Gravitational Lensing Magnification

• Applicant: Professor Dr. Hendrik Hildebrandt
• Subject Area: Astrophysics and Astronomy
• Term: from 2012 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 215116707

Weak gravitational lensing (WL) has been recognised as one of the most powerful techniques to study the nature of dark energy (DE), to test general relativity (GR), and to understand the relationship between visible and dark matter (DM) structures. While most researchers in this field use the shear effect of WL for these studies I have begun to establish the magnification effect as a competitive tool, which complements the shear and allows some new, unique measurements that are not possible with the shear. The Emmy Noether group proposed here will further develop and apply these methods to yield the first astrophysically relevant measurements of this kind. We will measure the magnification induced by galaxies with redshifts up to z ~ 1.4 from CFHTLS and KiDS data. In this way we will constrain DM-halo masses and relate them to stellar masses, spectral types, etc. We will also measure the dust profiles of these galaxies out to several Mpc using the magnitude-shift effect. Furthermore, our mass measurements of high-redshift clusters from SpARCS and KiDS will be an indispensable contribution to understanding cluster formation and measuring the galaxy cluster mass function, at redshifts hard to access by other methods. Eventually, by combining the dust- and DM-halo measurements of galaxies with clustering measurements in several redshift slices we will measure magnification tomography and thereby test GR and constrain the nature of DE.

• DFG Programme: Independent Junior Research Groups